Darren Clarke, Open champion. Easy to say, hard to believe. But that was the story told on Sunday as the big man from Dungannon walked strong and proud through the squalls, all the way up the final hole theatre at Royal St George's to claim the greatest prize in golf.

At the age of 42, in the supposed twilight of a distinguished career, the Northern Irishman followed his countryman and one-time protege Rory McIlroy into the role call of major champions with a three‑shot victory. It was a victory for pure talent and for the Everyman. In an era of the golfer athlete, Clarke is the cigar‑smoking, Guinness‑drinking proof there is more than one way to make history in this crazy game of ball and club.

The winning putt, uproariously greeted in the stands around the 18th green, dropped in from all of three inches. But the journey to that moment had taken Clarke through triumph and despair both on and off the golf course.

He had won more than 20 tournaments around the world, but never won the big one. He had played a distinguishing role in five Ryder Cup teams, never more so than in 2006 at the K Club, when he performed brilliantly for Europe just a few weeks after the death of his wife, Heather. Yet for all that he had never gained entry into the exclusive club reserved for major champions – a rotten injustice for a golfer acknowledged by his peers as one of the most naturally gifted of his generation.

Injustice, be gone.

Afterwards, he paid tribute to his deceased wife and to his two sons, Conor and Tyrone. The boys watched from home in Northern Ireland as their father showcased the skills he learned in his youth and which he recently became reacquainted with after moving from London back home, to Portrush.

"In terms of what's going through my heart, there's obviously somebody who is watching down from up above there, and I know she'd be very proud of me. She'd probably be saying, I told you so," he said of the late Heather Clarke. "But I think she'd be more proud of my two boys and them at home watching more than anything else. It's been a long journey to get here. It's incredible – it really is. It's for the kids."

Clarke's victory continues the remarkable run of success in major championships for Northern Ireland. It now boasts three victories in 13 months. Graeme McDowell won a US Open at Pebble Beach last summer, McIlroy won the same title at Congressional last month, and now this. Not bad for a nation of a million people. By comparison, the United States's (population, 300m) total of major victories over the same period stands at zero.

Of those three wins it would be fair to say this one came as the biggest surprise – shock even – but as the week progressed on the Kent coast it began to make more and more sense.

After three rounds in the 60s, Clarke began the final 18 holes on Sunday with a one-shot advantage. He holed from 20 feet for a par four at the 1st. It was a wonderful strike against adversity and just the kind of thing that sets a man believing this might be his day.

His lead doubled with a birdie at the 2nd and then stretched to three when his playing partner, Dustin Johnson, bogeyed the 3rd. The young American, who ultimately finished tied for second with Phil Mickelson, hits the ball further than some people go on holiday.

While there is something to be said for brute strength it will only take you so far on a day like this, in a place like this. Subtler arts were required and in that Johnson, like a Clydesdale in a Group One at Ascot, found himself seriously over‑matched.

Clarke has links golf running through his veins. He understands the importance of the ball flight – the lower the better – and that a golfer has no better friend than par in the wind and rain that swept across the golf course all day. A famously impatient man, he also found it within himself on this day of days to wait for the championship to come to him. And come it did.

His scoring highlight came at the par‑five 7th, where he holed from 30 feet for an eagle, the perfect riposte to an earlier eagle at the same hole by the charging Mickelson who had briefly taken a share of the lead. But the true beauty of his performance lay in its incremental parts. A cut shot here, a running hook there, a four-foot putt rammed into the back of the cup – like a painter laying down his brush strokes until, finally, the masterpiece is complete.

On a couple of occasions the bounce went his way, but for every piece of good fortune there was a putt that lipped the hole and somehow stayed above ground. There was no luck in this victory, only sweetness and redemption. It was not so long ago that Clarke was written off by some "experts" – a premature dismissal that apparently spurred him on.

"You know, bad times in golf are more frequent than the good times," he said, eyeing the Claret Jug beside him.

"I've always been pretty hard on myself when I fail because I don't find it very easy to accept that. And there's times I've been completely and utterly fed up with the game. But friends and family say, get out there and practise and keep going, keep going, keep going, and that's why I'm sitting here now."